Art of coking oils



31, 1929. D. R. WELLER ET AL 1,741,895

KRT OF COKING OILS Filed April 8, 1922 3 Sheets-Sheet 1 {Janie/ Z i ZZer Dec. 31, 1929.

D. R. WELLER ET AL ART OF GOKING OILS Filed April 8, 1922 5 Sheets-Sheet 2 Dec. 31 19 29. D. R. WELLER ET AL ART OF COKING OILS Filed "April 8. 1922 5 Sheets-Sheet 3 naegz wax lit Fatented s'rres DANIEL B. WELLER AND LOUIS LINK, 0F BATON ROUGE, LOUISIANA, ASSIGNORS T0 STANDARD Oll'L DEVELOPMENT COMPANY, A CORPORATION OF DELAWARE 1 or commit orns Application filed April 8, 1929. Serial No. 550,731.

The present invention relates to the distill'ation of petroleum oils, and more particularly to the dry or coking distillation of such oils with fractional separation of the distillate constituents. It will be fully understood from the following description, illustrated by the accompanying drawings, in which:

Fi re 1 is an elevation of the distillation and overhead equipment suitable for carrying outthe present invention, the overhead eqpip'ment being shown in part diagrammatt ca ly;

Fig. 2 is a plan view of the end of the still, showing the dome;

Figs. 3 and 4 are sectional views showing the construction and arrangement of the con densing and fractionating towers;

Fig. 5 is a side elevation of one end of the still showing the dome in section; and

Fig. 6 is an elevation of a modified equipment for carr ing out the invention, shown in part dia mmatically.

Referring more particularly to the form of construction of Fig. 1 of the drawings, the numeral 5 indicates a coking still mounted upon a suitable furnace setting 6. A. charging line 7 serves for the introduction of oil into the still. Near one end the still is provided at its top with an enlarged dome 8, which may suitably be a dome of generally cylindrical shape. From near the to of the dome vapor outlets 9 are provided, t ere being two in the construction illustrated. The cross sectional area of the dome 8 and of the outlets 9 are such as to permit the vapors evolved in the still tobe taken ofi substantially as fast as formed when the rate of formation is such as to completely eliminate all of the volatilizable constituents of the oil in from 10 to 18 hours. The outlets may suitably be 1/6th the diameter of the dome, or larger. With a cylindrical still of the usual type the diameter of "the dome may suitably be from one-third to one-half the diameter of the still. The height of the dome is preferabl not less than one-half the diameter of the stil Thus with a still of approximately 14 feet in diameterand 40 feet in length, capable of receiving a change of from 40 to 50,000 gal- Ions, the demo 8 may suitably be about six feet in diameter and the vapor pipes 9 each twelve inches in diameter.

The internal construction of the dome is illustrated most clearly in the sectional view thereof in Figure 5. Below the openings 10 of the vapor pipes 9 an inverted frustro-conical deflector 11 is secured to the wall of the dome. Somewhat below this is mounted a pan 12, the deflector and pan being so arranged that any condensate forming on the walls of the dome is deflected into the pan 12. From the pan 12 an outlet pipe 12 leads to the connection to the slop worm and wax line, as hereinafter more fully pointed out.

From the dome the vapor pipes 9 lead through lines 13 of about the same size as the vapor pipes to a series of fractionating and condensing towers, the arrangement of which is in general substantially the same as that described in our prior Patent No. 1,609,007, issued November 30, 1926. The vapors first enter tower 14, the construction of which is shown most clearly in Fig. 4. They passinto the chamber 15 in the base of the tower, rising through the tubes 16 and passing out through vapor pipes 17 into the chamber 18 in the base of the second tubular condenser 19, the construction of which is substantially similar to that of tower 1d. Condensate. from the chamber 15 of tower 14c discharges through pipe 20 and condensate from tubes 16 is collected in a pan 21 and discharged through pipe 22. Suitable connections are provided so that the cuts discharged through these pipes may be conducted individually or together through line 23 to cooling worm 24c or through line 25 to line 26 connecting with cooling worm 24:; or to line 27 connecting with cooling worm 28; or through line 31 to wax line 29, or to the run-back line 31. The entire condensate formed in the tower 19 is discharged through pipe. 32, which is provided with connections so that the condensate may be diverted through line 33 into cooling worm 34 or into the runback 35. From condenser 19 uncondensed vapors pass through pipes 36 into the base of tower 37, a sectional View of which is shown in Fig. 3. The vapors enter the latter below a grid 38 upon which is arranged suitable 43 to condenser worm distillation and reduce acking material 39, for example, stones. he vapors here pass through the tubes and make their exit through pipes 41 and 41. Condensate formed in the condenser 37 is discharged through pipe 42, which is pro vided with suitable connections whereby the condensate may be conducted through pipe 44 or through runback line 45 to the still.

The vapors passing out of the condenser 37 through pipe 41 enter the base of a fourth condenser 46, which may suitably be of the radiator type. Uncondensed vapors pass out of the condenser 46 through pipe 47 to the condenser worm 48. Condensate formed in condenser 46 is discharged through pipe 49 and connections are provided so that it may be conducted back to the still through runback line 50 or through pipe 51 to cooling worm 52 A portion of the vaporsfrom tower 37 may pass out through pipe 41 into cooling coil 53.

The arrangement of condensers and connections permits of the greatest flexibility in the operation of the still, the mode of handling the distillates being substantially that of the patent above referred to. In operating in accordance with the present invention, however, the heating of the charge may be carried out at a rate such as to reduce the time required for eflecting coking of the oil treated by one-third to one-half. It has hitherto en necessary in distilling oils to carefully fire the still so that the coking process, from the firing of the still to the completion of the coking process requires from 24 to 48 hours, the time depending upon the type of crude.

In the prior processes, when the temperature of the still reached say, 680 to 720 F., the greatly increased evolution of vapors made it necessary to slow down the rate of the fires very considerably and in consequence of this, the cracking period was materially extended and the destruction of valuable wax-bearing viscous distillates increased.

In accordance with the present process the heating of the still is so conducted that less than 18 hours is required from the time of firing to the coking of the still. Thus with light Mexican crude oil it has been found convenient to carry out the run from firing to coking in 15 to 18 hours and for oils such as Mid-Continent crude and Homer crude, in from 12 to 15 hours. The vapors evolved during the period following the reaching of a temperature of 680 to 720 F. pass freely through the system.

hThe results of the runs in accordance with t is differences from runs made under the longer schedule made necessary by the use of stills of the character hitherto in use, the size and capacity of the stills and the overprocess present several characteristic head equipment being identical in the comparative runs under the two types of schedules. The proportions and the character of the light products (naphtha, burning oil, and re-run distillate) are substair tially the same in the two types of processes. With respect to paraflin distillate, by the present process a greateryield is produced when. oils of the same viscosity are conr pared, or for equal yields of paraffin distillate, that produced by the present process has a better viscosity and a better cold test. The coke produced by the present process is materially less in quantity (about 10%) and, notwithstanding the more rapid heating of the still, less of it is burned to the bottom of the still. It has been noted with respect to the present process that the bottom of the still hardly reaches red heat during any stage of the run. The following illustrate the re sults produced by the present method of runnin oil.

Light Mexican crude was run from firing to coking in 15 hours and 30 minutes. The process yield 18.36% of naphtha of 57.8 gravity; 34.11% of re-run distillate of 39.7 gravity; 25.29% of parafiin distillate of 26 gravity having a viscosit of 74 Saybolt; 8.24% of a parafiin slop aving a gravity of 18.3 and a viscosity of 279 Saybolt; 12.09% of coke and 1.91% loss as waxtailings and gas.

Homer crude, run from firing to coking in about 13 hours and 30 minutes, yielded 31.39% of 61 Baum naphtha; 9.07% of 426 burning oil distillate; 28.89% of re-run distillate of 399 gravity; 24.91% parafiin distillate having a viscosity of 80 Saybolt; 2.16% of parafiin slop of 183 Baum; 2.33% of. coke and 1.25% loss.

Mid-Continent crude, run from firing to coking in about 14 hours and 30 minutes, yielding 25.18% of 556 naphtha; 14.28% of 421 burning oil distillate; 29.06% of 39 re-run distillate; 24.27% of paraflin distillate of 27.1 gravity and 92 Saybolt viscosity; 3.63% of paraffin slop of 17.7 gravity; 2.35% of coke and 1.23% loss.

A generally more effective arrangement of apparatus is illustrated in Fig. 6 of the drawings. The numeral indicates a still, which may be charged through line 61 and is provided with a dome 63, the relative dimen' sions of the still and the dome and the construction of the latter being substantially the same as in the -torm of apparatus previously described. The vapors from the still pass out of the dome 63 through lines 64, each having at least 1/6 the diameter of the dome. From these lines the vapors pass into a tower 65, the construction of which is substantially similar to that of tower 14, shown in Fig. 4 of the drawing. Condensate from the tuber: of tower 65 passes out through lines 66 and condensate from the base chamber of this lines 77 into the base of tower 78, which is substantially similar to tower 65 except that the condensate from the tubes is discharged together with the condensate from the base of the chamber through pipe 79. From pipe 79 the condensate from the tower 78 asses either into run-back line 80 or throng line 81 into cooling worm 82.

The vapors passing out of tower 78 are conveyed through at least two pipes 83, 83, into the base of tower 84, the construction of which is essentially similar to that of tower 37. Condensate from this tower is discharged through line 85 either into run-back line 86' or into the line 87, which conveys it to the cooling worm 88. The vapors uncondensed in tower 84 pass out through at least two vapor lines, 86, into the base of tower 87 the construction of which is substantially the same as that oi tower 78. The condensate from tower 87 is discharged through line 88, from which it passes into run-back line 89 or through line 90 into cooling worm 91. The vapors passing through tower 87" are discharged t rough lines 92 and 92. Line 92 discharges directly into condensing worm 93 and line 92" into condensing worm 94.

In running, particularly with the second form of equipment, during the period prior to that In which paraflin distillate is being given off, a. thorough and adequate separation. of vapors is effected in the towers aided by the runnin back of heavier, condensates to the still an their redistillation. A clean separation of the lighter fractions is consequently effected. During the period in which parafiin distillate or wax-bearing viscous fractions are being given off, only the condensate in tower 87", discharging through line 88, need be run back to the still, as each of the three preceding towers yields parafiin distillate whereas the condensate in the fourth tower may contain admixed gas-oil and re-"- fined distillate. With the second form of equipment illustrated, in the case of light Mexican crude oil, for example, the length of the run from firing to coking may be shortened from 20 minutes to one hour and the yield of paraffin distillate increased from 2 to 5% over the yields secured by the first described form of equipment.

Although the present invention has been described in connection with the specific details of an embodiment thereof, it is not intended that these details shall be regarded as limitations upon the scope of the invention, except in so far as included in the accompanying claims.

We claim:

1. A coking still comprising a cylindrical container, means for heating said container,

a cylindrical dome on the upper side of said container and, supported thereby, the diameter of said dome being not less than one-third the diameter of the container and the height of said dome being not less than one-half the diameter of the container, and a plurality of vapor outlets adjacent the top of said dome, each said outlet having a diameter at least one-sixth that of the dome, the proportions of said dome and outlets not substantially exceeding those required for free passage of the vapors without entrainment during maximum rate of evolutions thereof on complete distillation of the oil in said container to coke in a period not exceeding 18 hours. p

2. A coking still comprising a cylindrical container, means for applying heat to the lower portion of-the cylindrical surface, a cylindrical dome on the upper side of said container,-the diameter of said dome being not less than one-third and not more than one-.- half the diameter of the container, an inverted frustro-conical deflector in said dome, a receiving pan below said deflector, means for discharging oil from said receiving pan outside of said dome, and means for conducting vapor from said dome from a point above the pan and the deflector.

-DANIEL R. WELLER.

LOUIS LINK. 

